Xilinx, Inc.

Hongtao Zhang

Geoffrey Zhang

Winson Lin

Yohan Usthavia Frans

Zhaoyin D Wu

Kun-Yung Chang

Yu Liao

Yu Xu

Patrick Satarzadeh

Kevin Zheng

Ronan Sean Casey

Hsung Jai Im

Christopher J Borrelli

Declan Carey

Catherine Hearne

Ankur Jain

Arianne Roldan

Lokesh Rajendran

Geoff Zhang

Michael O Jenkins

Alan C Wong

Min Wu

Mohamed N Elzeftawi

Toan Duc Pham

Jinyung Namkoong

Siok Wei Lim

Hao-Wei Hung

Tan Kee Hian

Hong Sik Ahn

Yanfei Chen

Jin Namkoong

Ivan O Madrigal

Murtuza Z Cutleriwala

An example method for clock and data recovery (CDR) includes generating, in a set of slicers of a receiver, in addition to a data signal and a first error signal, at least one additional error signal. The method further includes receiving, at a frequency detector (FD) of a CDR unit of the receiver, the data signal, the first error signal, and the at least one additional error signal, and processing them to generate a FD output. The method still further includes multiplying the FD output by a user-defined FD gain, and adding the FD output, as multiplied by the FD gain, in a frequency path of the CDR unit.

Frequency detector for clock data recovery

Embodiments herein describe correcting nonlinearity in a Digital-to-Time Converter (DTC) by relaxing a DTC linearity requirement, which results in the correction being co-adapted with a DTC gain calibration loop which can operate in parallel with a DTC integral nonlinearity (INL) correction loop. In one embodiment, the DTC gain calibration loop and the DTC INL correction loop are constrained when determining a nonlinearity correction code to improve the likelihood they converge. Once determined, the nonlinearity correction code can be combined with an digital code output by a time-to-digital converter (TDC) to generate a phase difference between a reference clock and a feedback clock.

DTC nonlinearity correction

Methods, systems, and apparatus described herein make a multi-level PAM signal (PAM-N signal) at a transmitter using CMOS-based components. By forming the PAM-N signal at the transmitter, receivers do not have to recombine and/or realign multiple signals and only employs a single transmission line channel (or two transmission line channels in differential implementations) to convey the data stream to the receiver from the transmitter.

Ultra-high-speed PAM-N CMOS inverter serial link

Embodiments herein describe normalizing an output of a TDC in a DPLL to a resolution of the TDC. A DTC can delay a reference clock which is then input into the TDC. The TDC outputs a digital code indicating a time difference between the delayed reference clock output by the DTC and a clock generated by a DCO in the DPLL. This digital code is normalized to a resolution of the TDC and the result is filtered by a DLF.

DPLL timing normalization

A multiplexer (MUX) calibration system includes main MUX circuitry, first replica MUX circuitry, digital-to-analog (DAC) circuitry, detection circuitry, and control circuitry. The main MUX circuitry receives clock signals and outputs a first data signal based on the clock signals. The first replica MUX circuitry receives the clock signals and outputs a second data signal based on the clock signals. The DAC circuitry generates an offset voltage. The detection circuitry receives the second data signal and the offset voltage and generates a first error signal based on one or more of the second data signal and the offset voltage. The control circuitry receives the first error signal and generates a first control signal indicating an adjustment to the clock signals.

Calibrating a multiplexer of an integrated circuit

Apparatus and associated methods relate to an ADC-based digital receiver including a feedforward equalizer (FFE) that has m precursor taps and n postcursor taps to equalize the precursor portion, and to adapt postcursor intersymbol interference (ISI) through a predetermined equalization coefficient selected to counteract the noise boosting effect associated with the precursor equalization. In an illustrative example, the receiver may dynamically balance noise and ISI through adaptively determining a coefficient hpof a first postcursor tap of a first FFE and a coefficient hof a first postcursor tap of a second equalizer adapted to substantially reduce or eliminate additional ISI introduced by the first FFE. The first FFE may optimize ISI removal and noise reduction, for example. One of the coefficients hand hpmay be predetermined, and then the other coefficient may be iteratively adapted to trade off precursor ISI and postcursor ISI to minimize BER.

Digital noise-shaping FFE/DFE for ADC-based wireline links

A method relates generally to comparison of a communications system modelled with a behavioral model and implemented with a circuit realization. In this method, operation of the communications system is simulated with the behavioral model on a computing device to obtain a first pulse response. The simulating includes first equalizing first data with a first equalizer of the behavioral model to obtain the first pulse response. The circuit realization is operated to obtain a second pulse response. The operating includes: second equalizing second data corresponding to the first data with a second equalizer of the circuit realization to obtain the second pulse response. The second pulse response from the circuit realization is loaded to memory of the computing device. The first pulse is loaded to the memory of the computing device. The first pulse response and the second pulse response are compared with one another by the computing device.

Method and system for correlation of a behavioral model to a circuit realization for a communications system

An example method of clock and data recovery (CDR) includes adding a pre-defined offset to an output of a phase detector (PD) of a CDR circuit, and loading an accumulator of a frequency loop of the CDR circuit with a pre-defined load value. The method further includes detecting the phase of an incoming signal using a PD, and determining that the CDR has locked onto a real lock point. In some examples, the method further includes determining that the CDR has locked on a real lock point, and, in response to the determination, modifying the pre-defined offset to equal zero.

Phase detector offset to resolve CDR false lock

An equalizer circuit including a filter, equalization circuitry, and a filter adaptation circuit. The filter is configured to produce a linearized signal based at least in part on a received input signal and a nonlinear transfer function. The equalization circuitry is configured to filter inter-symbol interference (ISI) and detect one or more data symbols in the linearized signal. The equalization circuitry is further configured to produce an error signal indicating an amount of error in the detected data symbols. The filter adaptation circuit is configured to dynamically adjust the nonlinear transfer function of the filter based at least in part on the error signal from the equalization circuitry.

Nonlinear equalizer with nonlinearity compensation

A circuit for determining data error spacing in a data transmitter is disclosed. The circuit comprises a counter; encoding logic configured to receive an output of the counter, wherein the encoding circuit enables generating error spacing information; and a storage element configured to receive an output of the encoding logic.

Circuit for and method of determining error spacing in an input signal

A receiver circuit for receiving data is described. The receiver circuit comprises a phase detector configured to receive an input data signal; a frequency path circuit configured to receive an output of the phase detector; and a false lock detection circuit configured to receive the output of the phase detector and an output of the frequency path circuit; wherein the false lock detection circuit detects a false lock of the receiver circuit to the input data signal based upon an output of the phase detector and provides a frequency offset to the frequency path circuit. A method of receiving data is also described.

Data receiver circuit and method of receiving data

An example method of capturing an error distribution data for a serial channel includes: receiving a signal from the serial channel at a receiver in an integrated circuit (IC), the signal encoding data using pulse amplitude modulation (PAM) scheme having more than two levels; determining a plurality of symbols from the signal, each of the plurality of symbols encoding a plurality of bits; comparing the plurality of symbols with a plurality of expected symbols to detect a plurality of symbol errors; generating the error distribution data by accumulating numbers of the plurality of symbol errors across a plurality of bins based error type; and transmitting the error distribution data from the receiver to a computing system for processing.

Pam multi-level error distribution signature capture

A receiver includes: an automatic gain controller (AGC) configured to receive an analog signal; an analog-to-digital converter (ADC) configured to receive an output from the AGC and to output a digitized signal, wherein a most significant bit of the digitized signal corresponds to a sliced data, and a least significant bit of the digitized signal corresponds to an error signal; and an adaptation unit configured to control the AGC, the ADC, or both the AGC and the ADC, based at least in part on the digitized signal to achieve a desired data digitization and data slicing.

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San Jose, CA, United States of America

Hongtao Zhang